Sometimes, while 'creating', it's less like trying to cast my visions onto some medium and more like an exploration. Sometimes it's more fruitful just to let myself be guided by my impulses, my abilities, and the medium. I don't know if it works for everyone, but it works for me. One might worry that I'm being commanded by the medium, but what I make seems to be original, anyway.

I actually prefer writing by pen. It's more fluid. And since things can't be easily rewritten, you give a bit of thought before you commit something, and are always driven forward.

Knuth et al. notes, in an article on technical writing (http://tex.loria.fr/typographie/mathwriting.pdf):

"Towards the end of the editing process you will need to ensure that you don't have a page break in the middle of a displayed formula. Often you'll simply have to think up something else to say to fill up the page, thus pushing the displayed formula entirely onto the next page. Try to think of this as a stimulus to research!"

A pen sometimes functions in the same way. And if I find it's results undesirable, then I'll try not to think of it as a problem to fix, and rather as looking for a new medium to explore.

While limitations of the medium may help you be more creative, it doesn't mean that the same holds for me or most other people for that matter.

If, for example, you can find a scientific study that demonstrates that people are more creative with a pen than a word processor, then I would be interested.

For me, one should strive for ideas that transcend the particulars of existing mediums. Such ideas are more likely to be influential in the long term.